The present invention relates to a tire design method, a program for the same, and a tire manufacturing method using the design method.
Since a tread pattern of a pneumatic tire has significant influence on the hydroplaning performance, braking performance, and noises, there are demands for designs of tire tread patterns having optimized topology and shapes.
When a tire tread pattern is designed, a design plan satisfying performance requirements is made based on knowledge of the related art, experiences, and limitations on designing. One approach for verification of the design is to check whether the performance requirements are satisfied or not using a structural analysis. When it is revealed at this stage that the performance requirements are not satisfied, the design is corrected, and a structural analysis is conducted again to verify the design. This process is repeated until the performance requirements are satisfied, and a design plan is thereby finalized.
According to the design method in the related art, no guarantee is given on whether a design plan finalized within a range set based on design limitations provides optimal values or not. Since the method involves the process of repeating designing, structural analysis, and re-designing, a design task will require an enormous amount of time.
In general, a genetic algorithm is frequently used for the numerical optimization to optimize the design of a tire tread pattern (for example, see U.S. Pat. No. 6,531,012 B2). However, there are a great number of individual genes in the case of pattern designing of a wide area. Then, the computational cost is increased, and the approach is not effective enough to be used for practical design tasks.
Layout optimization techniques employing the finite element method includes the ECAT (Evolutional Clustering Algorithm for Topological Optimization). According to the ECAT, a structure of interest is regarded as an individual body, and elements are classified according to the magnitudes of their evaluation indices which are determined according to the problem to be solved. A global distribution of the evaluation indices in the structure is obtained, and actions of removing or adding each class of elements having small evaluation indices one after another are regarded as behaviors. Then, a layout is decided through evolution of such behaviors. Although the ECAT has been used for layout optimization problems in mechanical structures such as cantilevers, no application of this method to a tire tread pattern has been known.